The first trump was not a magus. In the French pattern he is Le Bateleur, a mountebank, a market conjuror, the man running the cup-and-ball game at a trestle table. In Italian decks he is Il Bagatto or Il Bagattella, a word suggesting a trifle or a thing of no value. He is the lowest of the trumps and worth the least, and in the game his interest lies precisely in being the weakest card that still beats every suit card, which makes him both trivial and dangerous to hold.
The promotion from swindler to adept happens in the eighteenth and nineteenth centuries. Court de Gebelin, in 1781, recast him as an Egyptian magician; the occult tradition after him identified him with Hermes and with the divine artificer, and the table of props became the four elements laid out as tools. That reading requires the four suit emblems to be present on the table, which in the older decks they are not consistently. The lemniscate above his head and the roses and lilies at his feet are from Pamela Colman Smith's 1909 drawing and appear nowhere earlier.
The older meaning has never entirely gone away. Readers who work with the Marseille pattern frequently keep the trickster in the card, and read the first trump as skill without depth, as presentation, as sleight of hand, or as a person whose competence is entirely real but whose intentions are not yet legible. That is not a reversed reading and it does not need to be. It is the card's first documented sense, and it sits underneath the modern one about will and manifestation rather than opposing it.